APLICATION OF FLOW ZONE INDICATOR METHOD IN RESERVOIR CHARACTERIZATION AT A1 SAND OF BEKASAP FORMATION, SOUTHERN MINAS FIELD

• Main Author: Setyawan, Amin
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/25455
• Institution: Institut Teknologi Bandung

<p align="justify">Minas field is the largest oil field in Indonesia that has been producing more than 4.6 billion barrels of oil or 53% of the initial oil in place (OOIP) estimates. As the oil production rate is decline and the inability of secondary water flood operations to recover more than 4 billion barrels of remaining oil, Minas field offers a huge enhanced oil recovery (EOR) prospect. After several laboratory and field trials have been conducted to find the best tertiary recovery technology, chemical flooding has been identified as the most viable EOR technology for Minas Field to further enhance oil recovery and extend its economic life. <br /> <br /> Application of current reservoir model using lithofacies concept in Minas Field was unable to answer the needs in supporting the chemical flooding technology which will be developed. This caused the reservoir simulation model often fails to comprehend the nature of reservoir heterogeneity as the most important factor in predicting the oil recovery and chemical flooding performance in the reservoir. Consequently, a new reservoir model is needed to recognize the variation of reservoir quality in a more detail scale, provide better understanding of irreducible oil saturation (Sorw) distribution as potential recovery target, and reduce the uncertainty of permeability value and its distribution in the reservoir. <br /> <br /> In this study, an improved reservoir characterization method, based on hydraulic flow unit identification using flow zone indicator (FZI) method according to Amaefule et al., 1993, is applied in the Minas A1 sand reservoir to better understand the reservoir characteristics in defining the nature of reservoir heterogeneity in a more detail scale. <br /> <br /> The analysis on the Minas A1 sand reservoir gives the FZI values of 1,2 to 28,6. Based on the FZI classification, A1 sand can be divided into five hydraulic flow unit which different degrees of reservoir quality. Hydraulic flow unit with high FZI is inferring a good reservoir quality, and hydraulic flow unit with low FZI is indicating poor reservoir quality. Each hydraulic flow unit is shown to have different pore throat characteristics, and consistently can be distinguished based on the pore throat size, texture and mineralogy, capillary pressure curve, and its irreducible fluids (oil and water) saturation distribution. <br /> <br /> A correlation function of FZI value with log data and special core analysis result in the cored wells is applied, in order to identify and locate the FZI value and its reservoir property. The hydraulic flow unit distribution was later validated using the actual flow test data in some producer wells, which indicated a strong relationship in demonstrating the fluid flow behavior of hydraulic flow units in the reservoir. The hydraulic flow unit with high FZI gives high productivity index (PI), in contract hydraulic flow unit with low FZI shows low productivity index. <br /> <br /> The FZI with hydraulic flow unit zonation and its reservoir property distribution in the study area is shown as three dimensional reservoir model using geostatistic method in Gocad software. The FZI modeling distribution shows good agreement with its reservoir property within the A1 sand reservoir. The area with high FZI value is corresponding to the area with good permeability and effective porosity, high initial oil saturation, and low irreducible oil saturation. This reservoir model offers wide varieties of practical field applications; this includes the areal selection for chemical flooding field trial, enhanced prediction accuracy of target recovery factor, as well as prediction of the chemical flooding performance in the reservoir.<p align="justify">